Windmills and other wind driven turbines generally comprise a series of blades projecting radially from a centrally located hub. This configuration provides several limitations. A first limitation is efficiency. The energy utilized to turn an object is referred to as torque. The torque is calculated at a force times a distance from the center of rotation. The force applied near the center of rotation has a significantly lower impact than a force applied towards the outer edge of the blades, although resistance is created along the entire length of the blade. A second limitation is the potential injury or death to birds. Turbines of common windmills have a plurality of blades, which are spatially configured, allowing birds to fly between the swirling turbines. This poses a risk whereby one of the blades could collide with the passing bird.
A first known blade discloses a rotor blade, which includes a main blade and an extension nap, which is translationally moveable relative to the main blade. The main blade and transition blade at least form an airfoil lifting surface of the entire blade. The dimension of the airfoil lifting surface is variable by translationally moving the extension flap relative to the main blade.
A second known reference discloses self starting vertical-axis wind turbine, for economically competitive power production by driving large grid-corrected AC generators. The wind turbine includes a variable blade pitch-angle from 0 to 60 degrees, wherein the blades following variable wind speed for maximum efficiency and to keep constant turbine speed; a variable blade camber to optimize lift-to-drag ratio, controlled by pitch and cyclical variation of incidence-angle; improved airfoil shape of cambered blades; low cost automatic gear-train for two constant turbine speeds; protection against overload and prevention of power surge during wind gusts; low stress three-legged high tower assembled with nacelle and tail structure on ground level. This enables a tower to be built to any height required to harness maximum wind energy.
Yet another known embodiment discloses a wind or water flow energy converter that includes a wind or water flow actuated rotor assembly. The rotor includes a plurality of blades; the blades of are variable in length to provide a variable diameter rotor. The rotor diameter is controlled to fully extend the rotor at low flow velocity and to retract the rotor, as flow velocity increases such that the loads delivered by or exerted upon the rotor do not exceed set limits.
While another known embodiment discloses a rotation shaft which is installed in the center of a wind turbine. Blades are secured to the rotation shaft to be circumferentially spaced apart one from another. Each blade has a lattice composed of transverse lattice elements and longitudinal lattice elements which are plaited to cooperatively define a plurality of spaces. In each space, a rotation adjustment piece is coupled to a first portion of a lattice element to be capable of rotating between a closing position where it closes a predetermined number of the spaces and an opening position where it opens a predetermined number of the spaces, so that the blades as a whole can be rotated irrespective of a wind direction. Electricity is generated using wind applied to the rotation shaft through rotation adjustment pieces.
And another known embodiment discloses a multi-axis turbine with an external upper covering, a tower structure with a plurality of vertical elongated members connected to each other with supporting horizontal elongated members, and a plurality of smaller blades on a rotation connected to a tower structure with a plurality of the rotation. One embodiment includes impact impellers connected to a rotation creating a swept area with a height to diameter ratio of greater than four. In one embodiment the impact impellers are connected to a rotation means thereby creating a swept area with a height to diameter ratio of greater than ten.
While another embodiment discloses a power plant which extracts energy from a free flowing fluid by means of a transverse mounted generator with its rotor extending downward into the flow. Runner blades with hinges attain the greatest surface area when the flow is tangent to and in the same direction as the rotor rotation. The hinges fold the runner blades to minimize the surface area proportional to drag when the blades oppose the flow. The generator with feedback control charges batteries, produces hydrogen fuel by electrolysis of water, or further couples to a DC motor coupled to an AC generator. Other features optionally perform such tasks as adaptively locating the generator in the maximum velocity flow, controlling and communicating the state of charge of the battery, or gauging and controlling the electrolysis process and communicating the fullness of the hydrogen gas output tanks.
Yet another embodiment discloses a design of a wind turbine blade and a wind turbine by which the power, loads and/or stability of a wind turbine may be controlled by typically fast variation of the geometry of the blades using active geometry control (e.g. smart materials or by embedded mechanical actuators), or using passive geometry control (e.g. changes arising from loading and/or deformation of the blade) or by a combination of the two methods. A method of controlling the wind turbine is also disclosed.
While another embodiment discloses a wind turbine system, which incorporates a variable blade assembly including adjustable sails and wing shaped masts expanding the wind velocity capture envelope. The blade assembly turns a hydraulic pump, which pressurizes fluid and stores the pressurized fluid in a chamber in the support tower. Pressurized fluid is directed via an electronically controllable proportioning valve to a hydraulic motor, which is coupled to an electric generator. A computer control module operates the proportioning valve regulating pressure to the hydraulic motor, maintaining generator rotational speed, and providing consistent output frequency to the power grid. Stored energy in the high pressure tank is used to continue generator operation after the winds cease, allowing early warning notification to the power management system of impending power loss. Residual pressure maintained in the high pressure tank allows restart operations via hydraulic pressure rather than power grid energy drain. On site high energy capacitors store additional energy.
And another embodiment discloses a wind turbine capable of varying active annular plane area by composing such that blades are attached to a cylindrical rotor movable in the radial direction of the rotor, the blades being reciprocated in the radial direction by means of a blade shifting mechanism connected to the root of each blade, or the blade itself is divided so that the outer one of the divided blade is movable in the radial direction. With this construction, the: wind turbine can be operated with a maximum output within the range of evading fatigue failure of the blades and rotor by adjusting the active annular plane area in accordance with wind speed.
Common windmills comprise a plurality (generally three) of masts or blades extending from a central hub. The design of the blades must be structurally sound to accommodate the applied forces. This requirement dictates a heavier construction to the masts or blades. The heavy construction increases the inertial force, which reduces the rotational speed of the turbine assembly. The mass of material increases the cost of fabrication, transport, and the like to the site. Alternately, exotic materials and structural designs can be used to reduce the weight, while increasing cost and complexity of fabrication.
Wind studies show that as the velocity of the wind doubles, the power of the wind or water is cubed. Thus, if a turbine at 12 MPH wind generates 10 watts of power, at 24 MPH it will produce 1,000 watts of power.
A turbine will increase speed as the velocity of the air or water is sped up. The power of a generator is also increased as the rotational speed is increased. The power of the generator is not necessarily the same power curve of the turbine driving the generator. Therefore, losses can be expected because of the power mismatch between turbine and generator.
The described device monitors the rpm of a generator either directly or indirectly and provides a value, which corresponds to the rpm of the turbine. This in turn, is used to determining the amount of load (power) to be generated.
The angle difference of wing and wind is known as the Angle Of Attack (AOA). Experiments have determined that the optimum AOA is approximately 28° in a “climb angle” for a blade or wing. The closer the AOA can be to the 28°, the more power that can be generated. Two methods can be used to keep this angle of attack (AOA) constant. One is to pivot the blades to make the proper angle. This would keep the RPM of the turbine rather constant. The changing of the blade angle is used on large turbines. The other method to have the AOA stable is to change the rpm of the turbine.
Therefore, a wind driven turbine wheel with improved efficiency and a focus on bird safety is needed. The method described below is to change the rpm and the power extracted to keep the blades of the turbine at the optimum AOA for maximum power generation. The method described will better fit small turbines with a diameter of perhaps no more than 150 feet.